Seals were once used to verify the authenticity of documents on clay tablets in Mesopotamia. Even with the invention of paper, they continued to be used along with a wax impression to authenticate the approval of a signatory to a document. Subsequently, with the advent of handwriting, signatures became the most popular and common mode of authentication of paper documents. Even today, government departments in many countries authenticate paper documents merely by using a rubber stamp along with an official's signature. Paper documents form the basis of today's business transactions and will continue to occupy an important place in commercial life. Unfortunately, forgery and paper documents go hand in hand.
Forgery of paper documents is becoming easier than ever before with the advancement being made in the technology of computers, scanners, printers and copiers. It is increasingly becoming possible to tamper with all kinds of valuable paper documents like checks, gift certificates, transcripts and legal documents. Documents can be counterfeited or the content, value, or ownership may be altered by forgery of the documents. Similarly, information could be altered so that rights and privileges are awarded to the wrong individual. In such scenarios, security practices for paper documents are required in order to:                a) Authenticate the document source        b) Verify integrity of the information on the document, and        c) Distinguish copies from originals.        
Advanced digital devices can be of assistance in this regard and various approaches have been proposed, see for instance US 2004/0100363 A1.
This invention reported here provides a simple, convenient and cost-effective method for carrying out all the operations described above without necessarily requiring major changes in operating procedures at an organization level and/or major investments in infrastructure.